Both HIV and Mycobacterium tuberculosis infection have emerged as a challenging clinical problem worldwide. The purpose of this work is to use in vitro models to study the immune regulation of T cells using PBMCs obtained from patients infected with HIV. Our intent is to define whether there are specific deficiencies in cytokine production that could be important in the ability to control HIV and other opportunistic infections. Moreover, we will also study the role of various costimulatory ligand interactions in mediating immune responses from PBMCs of HIV-infected individuals. This will specifically focus on how costimulatory ligand interactions such as CD40L/CD40 regulate both cytokine and chemokine production from T cells and antigen presenting cells such as macrophages and dendritic cells. Finally, we will determine whether agonists such as soluble CD40L are able to enhance the immune function of PBMCs in vitro as a prelude to using this reagent as a therapeutic for treatment or vaccine adjuvant. Over the past year we have optimized plasmid DNA vectors encoding HIV specific antigens as well as costimulatory molecules that will be used in a vaccine trial in primates. By using plasmid DNA vectors that have been optimized for expression in vivo for primates as well as humans, these experiments in the primates may provide information as to what the immune correlates of protection that will be needed for successful vaccination in humans.